Volvo - S80 :: Knocking Noises From All Four Corners

It makes knocking noises from all four corners, but mainly, when I make a hard right turn and it knocks it feels like the guts is going to fall out of it. It leaks tremendous amounts of oil from one side of the car to the opposite under the engine, but on checking the oil level, it does not require much topping up. Sometimes when making a hard turn, it's like there is no power steering. After spending copious amounts of money on it, and the problems not going away, the mechanic said to get rid of it. Also, when unlocking the doors manually or by remote, the back left passenger door makes a loud electrical buzzing noise that only started happening after the mechanic fixed the warning lights that kept coming up. That door no longer opens from the outside which means it won't pass a warrant. It was suggested it might be the solenoid? After getting into the car, you can hear a buzzing coming from around the radio area, and I haven't even inserted the key yet. It's such nice looking car and when it drives right, is awesum..